1diff --git a/pyscf/lib/misc.py b/pyscf/lib/misc.py
2index ed43689ff..a8a0d0e20 100644
3--- a/pyscf/lib/misc.py
4+++ b/pyscf/lib/misc.py
5@@ -42,8 +42,6 @@ if h5py.version.version[:4] == '2.2.':
6 sys.stderr.write('h5py-%s is found in your environment. '
7 'h5py-%s has bug in threading mode.\n'
8 'Async-IO is disabled.\n' % ((h5py.version.version,)*2))
9-if h5py.version.version[:2] == '3.':
10- h5py.get_config().default_file_mode = 'a'
11
12 c_double_p = ctypes.POINTER(ctypes.c_double)
13 c_int_p = ctypes.POINTER(ctypes.c_int)